Keston c40 replacement

[galaxy_plumbing]

Hey guys,

be honest dont have much experience with system boilers, mostly combis and heat only ones. Ned to replace keston c40, got vaillant 630 plus system already as cust enquired. Just got this puzzle into my head as keston has 2 control knobs to set hw and ch separately and is not such an option on new vaillant. Can you set this in the menu or additional wiring is required.

hope somebody could give me some pointers before i go to job today.

cheers

 

[galaxy_plumbing]

forgot to add, house has ufh so need to get temp down. There is additional pump for ufh and connected to blending valve.

 

[Killy Bing]

Give vaillant a ring over it.
i imagine there is
are you putting weather comp on it?
Because then you would have that set up for ufh and still fire full tilt for hot water

 

[Destroyer2813]

Surley there's a cylinder stat and the blending valve on the underfloor manifold will reduce the temp for you so don't have to be done at the boiler

 

[Killy Bing]

Surley there's a cylinder stat and the blending valve on the underfloor manifold will reduce the temp for you so don't have to be done at the boiler

The hot water dial on the keston dictates the flow temp while heating the hot water.
Want it on full rate or you will never get it to temp
i think it acts as a W plan and satisfys the hot water demand first.

then you can run the ch at a much lower flow temp making it more efficient than running it at high then blending it down at the ufh

pretty sure the only way to achieve it on a vaillant is to weather comp it and send it to a pretty low curve.

 

[Ermintrude]

What a load of tosh! The Keston won't be wired up correctly will just have a s/l so simply wire it as an s or s plan plus. The ufh can take a flow of upto 85c and blending mix it down. Don't worry. I would be more interested in the valliant a expansion and the drop in pumping head. Think the keston is 25m and the valliant is 15m.

 

[galaxy_plumbing]

looking at the manuals its 30 and 250. anyway, will call vaillant tomorrow, had tough day and feel like monkey working years in prison camp.

 

[galaxy_plumbing]

*sorry 25 for vaillant

 

[TBServices]

Vogue system allows for separate flow temps with a normal s plan.

 

[Ermintrude]

Vogue don't do a 40kw tho!

 

[Ermintrude]

Had this same issue...there are 20 odd left to do. All will be getting Worcester 40 cdi regular and mag 25 - 180 plus a Magna clean. 50l expansion existing.

 

[galaxy_plumbing]

dont tell me that, boiler on the wall already

 

[TBServices]

Built in diverter?

 

[Ermintrude]

Valliant is a lot smaller than keston on output. What loads have u worked out for system? Ufh is low density heat so if your a bit undersized that's ok. (Long slow low temp burn for ufh)

 

[galaxy_plumbing]

its system boiler, cust wanted 30kw as old keston was too big for his system.